Localized Dynamic Channel Time Allocation

ABSTRACT

Techniques for localized dynamic channel allocation help meet the challenges of latency, memory size, and channel time optimization for wireless communication systems. As examples, advanced communication standards, such as the WiGig standard, may support wireless docking station capability and wireless streaming of high definition video content between transmitting and receiving stations, or engage in other very high throughput tasks. The techniques help to deliver the desired user experience in such an environment and support desired performance levels for latency and throughput while controlling memory footprint.

TECHNICAL FIELD

This disclosure relates to communication protocols. In particular, thisdisclosure relates to latency, data memory size, and wireless channeltime utilization optimization for wireless communication systems.

BACKGROUND

Continual development and rapid improvement in wireless communicationstechnology have lead the way to increased data rates and broad wirelessfunctionality in many different environments, including the home andbusiness environments. These developments and improvements have beendriven in part by the widespread adoption of digital media, includinghigh definition video and music. The most recent developments inwireless connectivity promise new functionality and data rates farexceeding rates that the 802.11n and the 802.11TGac standards provide.These recent developments include the Wireless Gigabit Alliance (WiGig)and 802.11TGad 60 GHz wireless specifications.

The 60 Ghz specifications provides data transmission rates of up to 7Gbps in a single stream, which is more than 10 times faster than thehighest data rate that the 802.11n multiple input multiple output (MIMO)standard supports. Another benefit of the 60 GHz specifications is thatdevices in the 60 GHz ecosystem will have the bandwidth to wirelesslycommunicate significant amounts of information without performancecompromises, thereby eliminating the current need for tangles of cablesto physically connect devices. WiGig compliant devices may, as examples,provide wireless docking station capability and wirelessly stream highdefinition video content directly from a Blu-Ray player to a TV withlittle or no compression required.

Multiple devices may be communicating such streams to multiple differentreceivers, and each device may compete for channel time to deliver thestream. To deliver the desired user experience in such an environment,there is a need to meet latency and throughput requirements whilelimiting memory footprint requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

The system may be better understood with reference to the followingdrawings and description. In the figures, like reference numeralsdesignate corresponding parts throughout the different views.

FIG. 1 shows an environment in which wireless stations communicate withone another.

FIG. 2 shows a network manager communicating service periodallocation(s) to a source station requesting channel time by sending aTraffic Specification element (TSPEC).

FIG. 3 shows a communication diagram for a source station communicatingwith multiple destination stations in a single service period.

FIG. 4 shows a communication diagram for the source stationcommunicating with multiple destination stations in a subsequent serviceperiod, in which the transmit channel allocations have been adjusteddynamically by the SP source station.

FIG. 5 also shows a communication diagram for the source stationcommunicating with multiple destination stations in a subsequent serviceperiod, in which the transmit channel allocations have been adjusteddynamically by the SP source station.

FIG. 6 shows an example of a station.

FIG. 7 shows a flow diagram for logic that implements a localizeddynamic channel allocation for a source station to communicate withmultiple destination stations.

DETAILED DESCRIPTION

This description relates to wireless communication under standards suchas the IEEE 802.11 standards or the WiGig standards, including the 60GHz wireless specification promoted by the Wireless Gigabit Alliance andthe IEEE 802.11TGad standard. Accordingly, the discussion below makesreference to Service Periods (SPs), such as those defined by the WiGigstandard. During the SPs, a source station will communicate,potentially, with multiple destination stations. The techniquesdescribed are not limited to WiGig SPs, however, and instead areapplicable to any wireless communication protocol that provides forallocations of channel capacity to stations. Different from counterpartsoperating in lower frequency bands, wireless modems operating in 60 GHzfrequency band often rely on high antenna gain, achieved throughmechanisms such as beam-forming using directional antennas, tocompensate the link margin loss in 60 GHz band. The techniques describedhere may be employed even when directional antennas are not used, but inwireless systems with directional antennas the techniques are oftenparticularly beneficial.

The stations may take many different forms. As examples, the stationsmay be cell phones, smart phones, laptop computers, personal dataassistants, pocket computers, tablet computers, portable email devices,people or pets, or processes or threads executed in memory by aprocessor. Additional examples of stations include televisions, stereoequipment such as amplifiers, pre-amplifiers, and tuners, home mediadevices such as compact disc (CD)/digital versatile disc (DVD) players,portable MP3 players, high definition (e.g., Blu-Ray™ or DVD audio)media players, or home media servers. Other examples of stations includemusical instruments, microphones, climate control systems, intrusionalarms, audio/video surveillance or security equipment, video games,network attached storage, network routers and gateways, pet trackingcollars, or other devices.

Stations may be found in virtually any context, including the home,business, public spaces, or automobile. Thus, as additional examples,stations may further include automobile audio head ends or DVD players,satellite music transceivers, noise cancellation systems, voicerecognition systems, climate control systems, navigation systems, alarmsystems, engine computer systems, or other devices.

FIG. 1 shows one example of an environment 100 in which stationscommunicate with one another. In this example, the environment 100 is aroom in a home. For example, the environment 100 includes a media player102 (e.g., a Blu-Ray™ player) that streams high definition video andaudio content to a high definition liquid crystal display (LCD)television (TV) 104. Similarly, a home media server 106 with a wirelessnetwork interface streams audio (e.g., MP3 content) and video (e.g.,MP4, AVI, or MPEG content) to multiple destination stations in theenvironment 100, including the laptop 110, the smartphone 112, and theportable gaming system 114. A network scheduler 116 provides networkmanagement functionality in support of whichever standard is in use inthe environment 100, such as by scheduling SPs for the stations underthe WiGig standard. Typically, one of the stations in the wirelessnetwork assumes the role of network scheduler.

A station in the network communicates its Quality of Service (QoS)requirements to the network scheduler 116 by sending, as one example, aservice request containing a Traffic Specification element (TSPEC) tothe scheduler 116. The TSPEC may take the form of a set of numericparameters, or may take other forms in other implementations. Dependingon the wireless channel time availability, the network scheduler 116 mayreject or accept the received TSPEC. Once a TSPEC from a station isaccepted, the network scheduler 116 will be responsible for schedulingenough wireless channel time, for example in the form of SP(s), to meetthe QoS requirements specified in the accepted TSPEC. The networkscheduler 116 communicates the scheduled channel time allocationinformation, such as SPs, to all stations currently associated with thenetwork ahead of time. Normally, a SP is associated with a sourcestation, one or more destination station(s), and is characterized by astarting time and duration. The SP allocations involving multipledestination stations may be created by the network scheduler 116 throughcombining multiple TSPEC requests issued by the future source stationand/or the future destination station(s). One reason for doing so is toleave sufficient fine-grained scheduling flexibility to the futuresource station so that it can adjust the sequence and duration ofcommunicating each of the destination stations based on the dynamicneeds. During a SP, the SP owner or the source station is entitled to aspecific window of time (as specified by the SP duration) to transmitinformation without other stations attempting to access the channel.Since the SP allocation information is communicated to all stationsbefore the SP starts, each station (including the destination stationsthat the source station will communicate with) knows ahead of time aboutthe SPs that are scheduled. Therefore, if a destination station knowswhen to listen for communications from the SP, and, if the destinationstation uses a directional antenna during the SP, the destinationstation can tune its receive antenna to the source station at SP's starttime.

As noted above, a requesting station may specify the source station forany requested SP allocation using a source station identifier (e.g., aunicast source address), and may specify one or more destinationstations. A multiple destination station identifier in the request mayspecify the multiple destination stations. The multiple destinationstation identifier may be, as examples, a broadcast identifier ormulticast identifier (e.g., an identifier established for a predefinedgroup of stations among all of the stations in the network). In otherimplementations, the requesting station may specify multiple destinationstations with individual identifiers for the destination stations.

Ordinarily, a source station that specifies a multiple destinationstation identifier is expected to transmit the same data stream to eachof the multiple destination stations. As an example, by specifying amulticast identifier, the source station is expected to communicate thesame data stream to each of the multiple destination stations includedin the multicast identifier (e.g., by performing a multicasttransmission of the data stream during the SP). However, the source endpoint may instead, during its SP, communicate individually with chosendestination stations, and may therefore communicate different datastreams to each of the destination stations.

Furthermore, the stations may implement a Reverse Direction (RD)protocol that permits the source station to act as a RD initiator thatoffers a destination station to act as a RD responder. As an RDresponder, the destination station has the opportunity to transmit databack to the RD initiator during the RD initiator's SP. The reversedirection channel may provide a source of allocation adjustmentinformation external to the source station for (as described in detailbelow) for dynamically adjusting transmit channel allocations within thecurrent or subsequent SP(s) for communicating to specific destinationstations. The RD protocol may be the RD protocol defined in the IEEE802.11 standards or the WiGig standards.

FIG. 2 shows the home media server 106 streaming high definitionaudio/visual content 202 to multiple destination stations in theenvironment 100, including the laptop 110, the smartphone 112, and theportable gaming system 114.

However, instead of broadcasting or multicasting the same data stream tothe destination stations 110, 112, 114, the home media server 106 mayindividually communicate separate data streams 206, 208, 210 to thedestination stations during its SP. In doing so, the home media server106 may execute its own scheduler logic to choose the destinationstations it will communicate with, determine transmit channelallocations for each destination station, and individually transmit anydesired data stream to each chosen destination station during thetransmit channel allocation determined for that destination station.

FIG. 3 shows a communication diagram 300 illustrating an example ofcommunication from the home media server 106 to the laptop 110 and thesmartphone 112 during the SP 301 for the home media server 106. In thisrespect, the home media server 106 acts as a source station, and thelaptop 110, smartphone act as destination stations. The home mediaserver 106 may communicate with additional, fewer, or differentdestination stations during its SP, however, and any other station mayact as a source station at some other point in time. Despite requestinga SP for multicast/broadcast, the home media server 106 individuallycommunicates with the laptop 110 and the smartphone 112. In particular,the scheduler in the home media server 106 divides its SP 301 intosmaller transmit channel allocations A1, A2, A3, and A4 for eachdestination station.

In the example shown in FIG. 3, the transmit channel allocations A1, A2,A3, A4 are allocations in time with durations of T1, T2, T3, and T4respectively. Four allocations are shown. The source station mayinitiate a reverse direction grant during any transmit channelallocation, although the example shown in FIG. 3 indicates that thereverse direction grant (RDG) indicators are set to zero. During A1 andA3 the home media server 106 communicates with the laptop 110. During A2and A4 the home media server 106 communicates with the smartphone 112.

Note that the home media server 106 could have specified a destinationidentifier in its SP request as either a broadcast identifier ormulticast identifier, or other type of multiple destination identifier.If a destination identifier is a broadcast identifier, then all stationsother than the source station are expected to listen for transmissionsfrom the source station during its SP, and they are expected to steertheir receive antenna towards the source station at the beginning of theSP. Therefore, to allow destination stations to enter power saving modeor to communicate to other destination stations during the SP (fornetworks with spatial sharing capability), the source station mayinstead specify in the SP request a multicast identifier which specifiesa smaller intended subset of stations that the source station maycommunicate with. Hence only those stations belonging to the intendedsubset as specified by the multicast identifier need to stay awake andsteer their antenna toward the source station as specified by the sourceidentifier, while the rest of stations within the network may enterpower saving mode or communicate to each other as desired.

During A1, the home media server 106 transmits an aggregation 302 of QoSData frames 304, 306, and 308. The home media server 106 may organizeand aggregate the QoS Data frames into media access control (MAC)-levelprotocol data units (MPDUs) carried by Physical (PHY) layer protocoldata units (PPDUs), for example. In particular, during the SP, insteadof using a broadcast/multicast address as target receiver's address, theSP owner and source station (the home media server 106) may use aunicast destination address to individually pick which destinationstation to send data to, and may steer its transmit antenna beam towardsthat chosen destination station. The home media server 106 also decideshow long and how often it communicates to a particular destinationstation within the bounds of the SP duration, and in light of otherpossible constraints, such as QoS or throughput requirements for thevarious destination stations. This kind of traffic schedulingflexibility, optionally in connection with traffic control information,provides dynamic channel time allocation features into the otherwisenormally static SP allocations. The dynamic channel allocations helpachieve memory size, latency reduction and channel usage efficiencyimprovement goals.

Four frame exchange sequences (FES1, FES2, FES3, FES4) are shown in FIG.3 during the transmit channel allocations A1, A2, A3, and A4. The firstand third FES are between home media server 106 and the laptop 110,while the second and the fourth FES are from the home media server 106to the smartphone 112. In the example in FIG. 3, the wireless channelbetween the home media server 106 and the laptop 110 is less reliablethan that between the home media server 106 and the smartphone 112. Inthe first FES, the laptop 110, within the required interframe spacing310, block acknowledges, with the B/ACK frame 312, successful receipt ofthe data frames 304 and 308, but indicates reception failure for dataframe 306.

The home media server 106 retransmits the second data frame as the dataframe 314. The laptop 110 sends an acknowledgement 316. The sourcestation may dynamically adjust any transmit channel allocation for anyparticular destination station. For example, in the next FES with thelaptop 110 during A3, FES 3, the home media server 106 may apply morerobust encoding (or take other steps to enhance data integrity) to sendthe data frames 322 (acknowledged by B/ACK 324). The home media server106 may either allocate a longer transmit channel allocation to send thesame amount of data, or send less data in the same transmit channelallocation (as A1). It is also possible for the home media server 106 toreduce the transmit channel allocate and send even less data to thelaptop 110.

In contrast, benefitting from a good channel to the smartphone 112, bothFES 2, in which the home media server 106 communicates the data frames318 and receives the ACK 320, and FES 4, in which the home media server106 communicates the data frames 326 and receives the ACK 328, aresuccessful without resorting to retransmission. Therefore, the homemedia server 106 may need more channel time to send the same amount ofinformation to the laptop 110 than to the smartphone 112. In general,the home media server 106 may dynamically make transmit channelallocation adjustments based on a wide range of criteria, includingallocation adjustment information local or external to the sourcestation (e.g., the poor channel condition between the home media server106 and the laptop 110).

Benefits in terms of latency, memory usage and channel time usage areachieved compared with static SP allocations between a unicast sourceand a unicast destination. When SP allocations with only a unicastdestination are used, particular traffic from a unicast source to aunicast destination has to wait for the next SP designated to it tostart flowing. Prior to that, the traffic must wait (therefore incurringlatency) and accumulate all traffic data during the wait (thereforeincurring higher memory usage). Note that, even though the networkscheduler 116 schedules the allocations based on the TSPEC for anyparticular traffic, unless the traffic parameters (e.g., throughput) arestatic and the wireless channel condition is static (therefore withfixed packet error rate (PER)), it is difficult if not impossible forthe network scheduler 116 to provide accurate allocations mainly for tworeasons. First, the TSPEC for the traffic cannot fully capture thedynamic characteristics of the corresponding traffic, especially forvariable bit rate (VBR) traffic such as AV streams handled by VBRCODECs. Second, the allocation information from the centralized networkscheduler is communicated to all stations associated with the networkahead of time due to processing delay and communication delay.Therefore, those allocations cannot track or reflect the real channelcondition the traffic experiences because the channel condition mightvery well change between the time the relevant SP allocations weregenerated by the network scheduler to the time the SP starts due to thedynamic nature of the wireless channel. By applying the localizeddynamic allocation techniques described in this disclosure to theotherwise static allocations from the network scheduler 116, thetechniques can effectively address both dynamic traffic and dynamicchannel condition issues that may arise, by adjusting the sequenceand/or duration of each traffic component within a SP. In addition tothe latency and resulting memory usage benefits, there are benefits inchannel time efficiency because any allocation time in the SP that turnsout to be extra (e.g., an amount over budgeted in case of poor channelquality that does not actually manifest itself) can be allocated tosending data to other destination stations. Given a normal distributionof the amount of extra allocation actually required for any giventraffic during any given SP, the average amount of extra allocationrequired for a dynamically adjusted SP is less than the sum of the extraallocations per individualized SPs. This is because the channels betweendifferent source and destination pairs are not independent of each otherin practice.

As noted above, the source station may consider, as examples, allocationadjustment information local to (e.g., measured at the source station),external to (e.g., received from a destination station or other source),or both external to and local to the source station, for making localdynamic traffic channel allocation decisions. As one example, foraudio-visual (AV) streaming applications, the AV source(s) usuallydictates the rate at which the AV traffic(s) flow towards destinationstations or other AV sink(s). The SP owner for the AV source(s) acceptsand buffers the data coming from the AV source(s), and then schedulesthe data transmission to one or more destination stations for the AVsinks. Since the AV sink(s) are supposed to closely follow the AVsource(s), the SP owner may allocate channel time to different AVtraffics sharing the same SP according to the amount of buffered datafor each active AV traffic with respect to their relative nominalthroughput ratio.

As one example, assuming the nominal throughput of AV1 is two times thatof AV2, the scheduler logic in the source station may start byallocating twice the amount of channel time to AV1 traffic compared toAV2 traffic. However, considering the allocation adjustment information,if the buffered data for AV1 is more than twice the buffered data forAV2 (e.g., due to a lower physical (PHY) layer data rate and/or moreretransmissions, such that less than the expected amount of AV1 datagets through within the allocated channel time successfully), then thesource station may dynamically allocate more channel time to AV1 to helpthe buffered data ratio for AV1 and AV2 move towards the nominalthroughput ratio and reverse (or at least reduce or stop) the bufferconsumption trend (which helps to limit the amount of memory required).

Similarly, if the buffered data for AV1 is less than twice of thebuffered data for AV2, then the source station may allocate more channeltime to AV2 to the same end. In this way, benefits to buffer size,latency and channel time usage may be achieved. In one implementation,the scheduler logic in the source station attempts, as its goal, to keepbuffer consumption and latency in check, instead of making the buffereddata amount ratio approach some nominal throughput ratio. However, thescheduler logic may use latter as a guideline to decide which directionto make an adjustment to the transmit channel allocations because thenominal throughput ratio might not always be accurate, especially invariable rate application scenarios.

The scheduler logic in the source station may increase a transmitchannel allocation for a variety of reasons. In addition to increasingthe transmit channel allocation when the channel condition is worse thanexpected (which results in lower PHY rate and/or more retransmissions),the source station may also increase the transmit channel allocationwhen the desired transmission rate is higher than expected, or for anyother reason. The desired transmission rate may increase, for example,for AV streaming with variable rate encoding, because the actual ratecan fluctuate above or below the nominal rate. Regardless of the reason,the dynamic allocation and adjustments described can react to the neteffect that the actual data amount in the transmit buffer does not matchthe nominal throughput ratio. As a result, the source station may adjustthe transmit channel time allocations. Continuing the previous example,suppose that the channel condition to AV1 and AV2 are both satisfactory,but the initial estimate of a 2-to-1 nominal throughput ratio isincorrect, and the actual ratio is 1-to-1. Then the net effect is thatthere would be continuous data accumulation in the AV2 traffic memoryqueue. As a result, the scheduler logic in the source station may adjustthe transmit channel allocations so that the source station allocatesmore channel time to AV2 to reverse or stop the accumulation of data inthe buffer. Thus, even in a complex traffic situation (e.g., includingvariable data rates), the dynamic allocation techniques canappropriately respond.

The traffic memory queue utilization is an example of information localto the source station. The source station may also consider externalinformation in making transmit channel allocation adjustments. Forexample, AV streaming data delivery time requirement information may besent to the source station, which may then use the information in thetraffic control process. As another example, a destination station maycommunicate receive data buffer capacity or overflow back to the sourcestation. In one implementation, a block acknowledgement with flowcontrol may use the optional flow control field RxBufferCapacity toinform the source station of how much empty buffer space is left in thereceiver. If the buffer space is overflowing, for example, the sourcestation may reduce the transmit channel allocation to that destinationstation to reduce the data arrival rate at the destination station. Ifthe buffer space is nearly empty, the source station may try to increasethe transmit channel allocation to increase the data arrival rate at thedestination station.

The source station may consider any allocation adjustment informationreceived from any source. As another example, the source station mayconsider information received in an Action frame that contains, e.g.,vendor specific steps for the recipient (e.g., the source station) totake, or noting how much buffer space remains at the receiver using aninformation element in the Action frame. As another example, thecurrently unused SequenceNumber field in a QoS Null frame may convey tothe source station how much room is left in a receive buffer at adestination station.

The dynamic channel time adjustment capability facilitates the sourcestation to quickly respond to the data needs of the destination stationsbased on any feedback. This in turn can minimize the buffer requirementson both sides of the channel because it minimizes the impact on thebuffer size from periods of non-transmission to any given destinationstation. Minimizing buffer requirements not only reduces cost, but alsomeans reducing the latency of a data frame traveling through the systemin constant rate application scenarios such as AV streaming.

FIG. 4 shows a communication diagram 400 for the source stationcommunicating with multiple destination stations in a subsequent serviceperiod, in which the transmit channel allocations have been adjusted. Asan example, the source station has extended A1 to encompass severaladditional data frames 402, kept A2 to encompass three data frames 404,and has eliminated A3 and A4. Similarly, the source station may addtransmit channel allocations instead of eliminating them.

FIG. 5 also shows a communication diagram 500 for the source stationcommunicating with multiple destination stations in a subsequent serviceperiod, in which the transmit channel allocations have been adjusted. Inthis example, the source station has changed the transmit channelallocation A3 to communicate to an additional destination station.Specifically, the source station now uses A3 to communicate the dataframes 502 to the portable gaming system 114.

FIG. 6 shows an example implementation of a station 600, in thisinstance the home media server 106. The station 600 includes atransceiver 602, one or more processors 604, a memory 606, and a userinterface 608. The transceiver 602 may be wireless transceiver, and thetransmitted and received signals may adhere to any of a diverse array offormats, protocols, modulations, frequency channels, bit rates, andencodings that presently or in the future may support WiGig serviceperiods or similar types of dedicated channel allocations, such as theGHz WiGig/802.11TGad specifications.

The processor 604 executes the logic 610. The logic 610 may include anoperating system, application programs, firmware, or other logic. Thelogic 610 includes local scheduler logic 612. The local scheduler logic612 executes within the station 600, as opposed to within thecentralized network scheduler 116, which handles scheduling, in general,for the stations in the network as described above. Depending on theimplementation, the processor 604 may be one or more processing units(e.g., multiple microcontrollers). The task partitioning among theprocessing units may be based upon many different factors, includingwhether real-time response or processing of a particular task isdesired. The local scheduler logic 612 may implement the processingnoted above, and described below with respect to FIGS. 6 and 7,including negotiating QoS requirements using TSPECs, processing thereceived channel allocations from the network scheduler, furtherscheduling transmit channel allocations within an SP (at any desiredlevel of granularity) to any number of destination stations, anddynamically adjusting transmit channel allocations. The fine-grained,localized scheduling and dynamic adjustment within a SP allocation maybe handled in real-time. Hence, the local scheduler logic 612 may beexecuted, for example, by a dedicated processing unit that may assistwith lower level hardware medium access control (MAC). Other real-timeimplementations may be employed, however.

The station 600 may save allocation adjustment information 618 in thememory 606 for consideration by the scheduler logic 612. The allocationadjustment information 618 may include information local to the station600, such as the buffer level of the data buffers 620 that temporarilyqueue data for transmission during the SPs, or the expected throughput,data rate, QoS, or other requirements for each destination station. Theallocation adjustment information 618 may also include informationexternal to the station 600, such as the buffer level of data buffers ina destination station, signal-to-noise ratio or other channelconditions, or other information.

The scheduler logic 612, based on the allocation adjustment information,may dynamically change transmit channel allocations for the current orsubsequent SPs. The dynamic changes may include: increasing the numberof destination stations communicated with during an SP, decreasing thenumber of destination station communicated with during an SP, changingthe destination stations communicated with during an SP, increasing(e.g., in time) one or more transmit channel allocations, decreasing(e.g., in time) one or more transmit channel allocations, and changingthe amount of data sent during a transmit channel allocation (e.g., bychanging the data encoding to be more or less robust). The schedulerlogic may make other changes to the transmit channel allocations.

FIG. 7 shows a flow diagram of logic 700 for local dynamic channelallocation. The local scheduler logic 612 may implement the logic 700 assoftware instructions executed by the processor 604, for example.However, the logic 700 may be implemented in hardware, or as acombination of hardware and software, including as or with dedicated orspecialized processors with the processing capability to provide, forexample, real-time adaptations to the transmit channel allocations.

A source station prepares the TSPEC to meet its traffic requirements(702) and communicates the TSPEC to the network scheduler 116 (704). Thesource station may send the TSPEC to the network scheduler 116 in an AddTraffic Stream (ADDTS) Request frame, for example. The network scheduler116 determines the start time and duration of the SP allocations, andcommunicates the SP allocation information to all stations associatedwith the network through beacons and/or Action announcement frames aheadof time. In particular, the network scheduler 116 acknowledges receiptof the TSPEC, and the source station receives the acknowledgement (706).In addition, the source station monitors for SP allocation informationsent from the network scheduler 116 to the station (708). The SPallocation information may arrive in an ADDTS Response frame sent by thenetwork scheduler 116 to the source station, and each destinationstation identified as a destination in the TSPEC in the ADDTS Requestframe. In other words, the source station awaits (and the destinationstations also receive) the SP information that confirms the SP duration,start time, and other SP information. The SP allocation information mayspecify a unicast source address, and a multiple recipient destinationaddress, such as a broadcast or multicast address, or other information.

The logic 700 makes a determination of the transmit channel allocations(TCAs) within a SP for any desired destination stations (710). Forexample, if the station 600 will communicate with three destinationstations during the next SP, and the relative throughput needed is2:3:1, then the logic 700 may determine that there will be threetransmit channel allocations (for example) with a ratio in aggregatedlength of 2:3:1 (e.g., 20 frames:30 frames:10 frames of data). Thesource station determines when a particular TCA has started, and thenindividually transmits data to the next destination station during theTCA (712). The SP allocation(s) from the network scheduler 116 may becreated by aggregating multiple TSPEC requests involving a common sourcestation and multiple destination stations. In this way, the networkscheduler 116 can give the source station the flexibility to decide atwhat sequence and duration it communicates to each of the destinationstations to optimize the latency, data memory size while meeting the QoSrequirements for each traffic stream. For example, the station 600 mayspecifically transmit to a particular destination station by specifyingthat destination station's identifier in outgoing frames.

The logic 700 may obtain allocation adjustment information (714) beforeor during the SP or any particular TCA, and may make dynamic transmitallocation adjustments at any time for the current or any subsequent SPor TCA (716). The logic 700 may obtain the allocation adjustmentinformation at discrete points in time, on some predetermined schedule,continuously (e.g., as an always running background process), asinformation received from other stations or entities in the network, orin other ways. The station 600 may offer reverse direction grants to thedestination station, and may use selected data returned by thedestination station during the reverse direction grant as allocationadjustment information (e.g., information concerning buffer level at thedestination station).

The local dynamic allocation process may continue for each transmitchannel allocation for each destination station. The allocationadjustment information may be local to the station 600 (e.g., bufferlevels in the station 600), external to the station 600 (e.g.,information received that indicates expected relative desired throughputto each of multiple destination stations, or buffer levels at adestination station), or may be any other type of information that thelogic 700 can consider to determine transmit channel allocations.

The methods, stations, and logic described above may be implemented inmany different ways in many different combinations of hardware, softwareor both hardware and software. For example, all or parts of the station600 may include circuitry in one or more controllers, microprocessors,or application specific integrated circuits (ASICs), or may beimplemented with discrete logic or components, or a combination of othertypes of circuitry. All or part of the logic may be implemented asinstructions for execution by a processor, controller, or otherprocessing device and may be stored in a machine-readable orcomputer-readable medium such as flash memory, random access memory(RAM) or read only memory (ROM), flash memory, erasable programmableread only memory (EPROM) or other machine-readable medium such as acompact disc read only memory (CDROM), or magnetic or optical disk.

While various embodiments of the invention have been described, it willbe apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible within the scope of theinvention. Accordingly, the invention is not to be restricted except inlight of the attached claims and their equivalents.

What is claimed is:
 1. A method, comprising: choosing a firstdestination station; obtaining, at a first source station, a firsttransmit channel allocation from network scheduler circuitry forindividual transmission to the first destination station within aservice period, the first transmit channel allocation being shorter thanthe service period; and during the first transmit channel allocationwithin the service period, individually transmitting from the firstsource station to the first destination station.
 2. The method of claim1, further comprising receiving, from the network scheduler circuitry, asecond transmit channel allocation for the service period, the secondtransmit channel allocation for individual transmission to a seconddestination station.
 3. The method of claim 2, further comprising:obtaining allocation adjustment information external to the sourcestation for dynamically adjusting the first transmit channel allocation,the second transmit channel allocation, or both.
 4. The method of claim2, wherein receiving the second transmit channel allocation comprisesreceiving the second transmit channel allocation at second sourcestation.
 5. The method of claim 1, wherein the first transmit channelallocation comprises a time duration allocation.
 6. The method of claim1, further comprising: adjusting the first transmit channel allocationfor use in a subsequent service period.
 7. The method of claim 6,wherein adjusting the first transmit channel allocation comprisesobtaining allocation adjustment information local to the source station.8. The method of claim 1, wherein the first destination station isspecified by a multicast address or a broadcast address transmitted fromthe first source station.
 9. A system, comprising: a transmitter; andnetwork scheduler circuitry in communication with the transmitter, thenetwork scheduler circuitry configured to: receive a request, from afirst source station, to individually transmit during a service periodto a first destination station from among multiple destination stations;determine a first transmit channel allocation within the service period,the first transmit period being shorter in extent than the serviceperiod; and transmit, with the transmitter, allocation information forthe first transmit channel allocation within the service period to thefirst source station.
 10. The system of claim 9, wherein the networkscheduler circuitry is further configured to receive a request, from asecond source station, to individually transmit during the serviceperiod.
 11. The system of claim 10, wherein the network schedulercircuitry is further configured to schedule a second transmit channelallocation within the service period for the second source station. 12.The system of claim 11, wherein the network scheduler circuitry isfurther configured to transmit, with the transmitter, allocationinformation for the second transmit channel allocation to the secondsource station.
 13. A device, comprising: source circuitry configuredto: select a first destination station from among multiple destinationstations; and generate a request to individually transmit to thedestination station during a service period; and a transceiverconfigured to: receive, from network scheduler circuitry, allocationinformation identifying a first transmit channel allocation for theservice period, a duration of the first transmit channel allocationbeing shorter than a duration of the service period; and responsive tothe allocation information, individually transmit to the firstdestination during the first transmit channel allocation.
 14. The deviceof claim 13, wherein the transceiver is further configured to receive amodification to the first transmit channel allocation for a subsequentservice period.
 15. The device of claim 14, wherein the modificationcomprises a time duration change.
 16. The device of claim 15, whereinthe first transmit allocation is one of multiple transmit allocationswithin the service period.
 17. The device of claim 14, wherein themodification comprises a data rate change.
 18. The device of claim 14,wherein the modification comprises an a revocation of the first transmitchannel allocation.
 19. The device of claim 14, wherein the sourcecircuitry is further configured to generate a request for themodification.
 20. The device of claim 13, wherein the transceiver isconfigured to send a message comprising a multicast identifierassociated with the first destination station.